JPH0519929U - Temperature sensor - Google Patents

Abstract

(57) [Abstract] [Purpose] Despite the fact that the contact force to the temperature sensing object can be obtained properly, it does not increase the heat capacity near the thin film thermistor, has excellent thermal response characteristics, is easy to manufacture, and ,
Provided is a temperature sensor capable of accurately fixing a fixing position when attaching a heat sensitive element to a tip of a metal plate. [Structure] A pair of elongated metal plates 2 having connection terminals 2e and 3e for connecting an external lead wire 6 at one end and narrow portions 2d, 3d for bonding a heat-sensitive element 5 described later at the other end. , 3, a holding body 4 for holding the connection terminal side in a state where the narrow portions of the pair of metal plates are brought close to each other in a substantially parallel manner, and a heat sensitive film 5b is formed on the insulating substrate 5a. A thermosensitive element 5 comprising a thin film thermistor having two electrode surfaces 5c formed on a thermosensitive film, wherein the electrode surface of the thermosensitive element is joined and fixed to the tip of the narrow portion of the metal plate; The recesses 6f and 7f having substantially the same size as the heat sensitive element may be formed at the tip of the narrow portion.

Description

[Detailed description of the device]

[0001]

[Industrial application]

 The present invention relates to a temperature sensor for detecting the surface temperature of a temperature detection target such as a rotating body or a stationary body used in a fixing device such as a copying machine or a printer, and detecting the surface temperature of the temperature detection target.

[0002]

[Prior Art]

 As a conventional contact-type temperature detecting device of this type, a contact-type temperature sensor for bringing a heat-sensitive element into contact with the surface of a heating roll, such as the temperature sensor disclosed in JP-A-63-205530, is mainly used. It has been.

This temperature sensor is arranged in a gap between a pair of strip-shaped metal plates having an outer lead portion for connecting an outer lead wire and a gap between the pair of metal plates, and is attached to the pair of metal plates. Provided on a surface of the thermosensitive element to which a conductive wire is electrically connected, a holder formed on at least one end of the pair of metal plates, and a surface of the thermosensitive element and the pair of metal plates that come into contact with the temperature detection object. And a thin film sheet.

[0004]

[Problems to be solved by the device]

 However, a temperature sensor having a holder at both ends of a pair of strip-shaped metal plates tends to have a large shape, and if there is only a limited space such as a fixing device such as a copying machine or a printer, this temperature sensor is not suitable. Occasionally it could not be installed.

Further, although the single-support type temperature sensor in which a holder is formed at one end of a pair of metal plates has an advantage that the shape can be made small, when a conventionally used bead thermistor is used, a heat-sensitive element is used. The conductor wire is usually as thin as about 60 μm, and the end of the metal plate on the side opposite to the holder is fixed by a flexible thin film sheet, so that it moves relatively freely.

Therefore, the heat-sensitive element may float above the surface of the thin film sheet due to twisting or vibration during mounting, and the heat-sensitive element may have to be fixed with an adhesive. As described above, when the adhesive is used, the heat capacity of the heat-sensitive element portion increases, which causes a drawback that the heat response characteristic is deteriorated.

Further, in order to increase the pressure contact force with respect to the temperature detection object, the width of the metal plate must be increased, but in that case, the total heat capacity increases. In order to avoid this, if the width of the metal plate is reduced, the pressure contact force becomes weak, heat conduction becomes unsmooth, and the heat response characteristic deteriorates in any case.

Further, the bead thermistor has a spherical shape, and the contact with the temperature-detected body becomes a point contact, which, in combination, provides a sufficiently satisfactory result in terms of thermal response characteristics. I couldn't do it.

The present invention solves the above-mentioned drawbacks of the conventional contact-type temperature sensor, is easy to manufacture, and the contact force to the temperature sensing object can be obtained without increasing the heat capacity of the heat-sensitive element. An object of the present invention is to provide a temperature sensor having excellent thermal response characteristics by using a thin film thermistor, and further capable of accurately fixing the fixing position when mounting the heat sensitive element on the tip of the metal plate.

[0010]

[Means for Solving the Problems]

 The present invention is based on means of a temperature sensor for achieving the above-mentioned object, and has a connection terminal for connecting an external lead wire at one end and a narrow width for joining a heat-sensitive element described later at the other end. A pair of elongated metal plates on which parts are formed, a holding body that holds the connection terminal side in a state where the narrow parts of the pair of metal plates are close to each other in parallel, and a thermosensitive film is formed on the insulating substrate. And a thermosensitive element comprising a thin film thermistor having two electrode surfaces formed on the thermosensitive film, wherein the electrode surface of the thermosensitive element is joined and fixed to the tip of the narrow portion of the metal plate. It is preferable that a recess having substantially the same size as the thermosensitive element be formed at the tip of the narrow portion, and the thermosensitive element be bonded and fixed to the recess.

[0011]

[Action]

 In the temperature sensor of the present invention, the pair of metal plates to which the heat-sensitive element is joined are formed with the outer sides being slanted and narrow toward one end where the heat-sensitive element is joined. The heat capacity of the joined parts becomes small, and it quickly adapts to the ambient temperature. Therefore, the amount of heat conduction from the temperature-sensing body to the pair of metal plates and the heat-sensitive element is small, and the temperature-sensing characteristics of the heat-sensitive element can be improved.

Further, since the shape of the narrow width of the metal plate toward the tip is the same as the stress of the bending moment with respect to the metal plate, the contact of the heat sensitive element with the temperature detection object due to the narrow width. The tactile force is not weakened, and therefore the heat conduction from the temperature-sensing body to the heat-sensitive element is performed well.

Further, since the heat-sensitive element is placed in the recess formed in the narrow portion of the metal plate and electrically connected, the heat-sensitive element can be connected and fixed in the correct position in the correct direction, resulting in positional deviation. It is possible to improve the variation in the thermal response characteristics caused by the above.

[0014]

【Example】

 Next, an example of implementation of the present invention will be described below with reference to FIGS. 1 and 2 show the manufacturing process of this embodiment. A is a lead frame in which a strip-shaped metal plate of stainless steel, kovar, nickel alloy or the like is formed by means of chemical etching or the like. As shown in the figure, the lead frame A includes a strip-shaped plate 1 having sprocket holes 1a formed at regular intervals in the longitudinal direction, and a pair of strips extending in a direction perpendicular to the strip-shaped plate 1 at regular small intervals. A plurality of elongated metal plates 2 and 3 are sequentially provided.

The metal plates 2 and 3 include narrow width portions 2a and 3a connected to the strip-shaped plate 1 and wide width portions 2b connected to the narrow width portions 2a and 3a and held by a mold by a holder 4 described later. 3b and narrow portions 2d, 3d connected from the wide portions 2b, 3b and having opposite edges formed in parallel and outer edges formed obliquely.

It should be noted that hole-shaped portions 2c and 3c, which are larger than the screw holes 4a formed in the holder 4, are formed at opposite edges of the wide portions 2b and 3b. Further, it is preferable that the widths of the leading ends of the narrow width portions 2d and 3d are narrowed to a width at which a thin film thermistor 5 described later can be bonded.

As shown in FIG. 1, the lead frame A has screw holes 4a formed in the hole portions 2c and 3c, and the wide portions 2b and 3b are made of a material such as insulating plastic. Then, the holding body 4 is molded by means such as transfer molding. Further, the hole portions 2c and 3c are not necessary depending on the shape of the holder 4 and the position of the screw hole 4a.

As shown in FIG. 3, the thin film thermistor 5 is made of SiC, manganese, cobalt, nickel on an insulating substrate 5a such as alumina having a thickness of 100 to 300 μm and a size of about 1.6 × 0.8 mm. A heat-sensitive film 5b formed by a known thin-film forming technique such as sputtering with a metal oxide such as is formed, and two electrode surfaces 5c are formed on both sides of the heat-sensitive film 5b. Is.

Then, as shown in FIG. 5, when the thin film thermistor 5 is joined to the narrow portions 2d and 3d of the metal plates 2 and 3, solder paste or the like is previously attached to the tips of the narrow portions 2d and 3d. A brazing material is applied by a known method such as screen printing, or a brazing material such as a solder paste is applied in advance on the electrode surface 5c of the thin film thermistor 5 by the same method as described above, and the electrode surface 5c of the thin film thermistor 5 is Are placed so as to be superposed on each other, joined by a method such as heating, and electrically connected.

In this way, after the two metal plates 2 and 3 are integrally held by the holding body 4, the lead frame A is cut from the narrow width portions 2a and 3a to obtain the temperature sensor shown in FIG. It In the figure, 2e and 3e are connection terminals for connecting an external lead wire (not shown).

As described above, in this temperature sensor, after the lead frame A is continuously molded, the holding body 4 is transfer-molded and the narrow width portions 2a and 3a are cut, so that many temperature Since the sensor can be manufactured continuously, the workability of production is significantly improved compared to the conventional single product processing.

Further, coupled with the high processing accuracy of the lead frame A, it is possible to extremely reduce the occurrence of defective products due to dimensional variation. The molding of the holding body 4 is not limited to the transfer molding described above, and the resin-molded holding body 4 may be assembled on the lead frame A.

Next, a second embodiment of the present invention will be described with reference to FIGS. 5 and 6 are views showing a manufacturing process corresponding to FIGS. 1 and 2 of the previous embodiment. The lead frame A in FIG. 5 has a narrower portion 2a than the lead frame A in FIG. , 3a is the only difference.

Then, in the holder 4 shown in FIG. 6, the narrow portions 2a and 3a are exposed and molded, and at the same time, the through hole 4b is penetrated between the narrow portions 2a and 3a to form the through hole 4b. An annular protrusion 4c is formed at the upper end, and an annular recess 4d into which the annular protrusion 4c is fitted is formed at the lower end, and a recess 4e is formed on the upper surface of the narrow portions 2d and 3d. A ridge 4f inserted into the recess 4e is formed on the opposite surface.

As shown in FIG. 9, the narrow width portions 2a and 3a are exposed and molded with the holding body 4, as shown in FIG. 9, the shrinkable tube 7 is covered on the external lead wire 6 soldered thereto. Insulating this part.

Further, as shown in FIG. 10, the annular protrusion 4c, the annular recess 4d, the recess 4e, and the protrusion 4f are formed above and below the through hole 4b, as shown in FIG. This is because if the holders 4 are sequentially stacked in this manner, the stacked state will not be displaced, and damage due to collision of the narrow portions 2d and 3d can be prevented. Apart from these, this embodiment is not different from the previous one.

Next, another embodiment of the lead frame A will be described with reference to FIG. 11. In this embodiment, a thin film having substantially the same outer dimensions as the thin film thermistor 5 is provided at the tips of the narrow portions 2d and 3d. The recesses 6f and 7f for positioning the thermistor 5 are formed by a method such as etching as shown in a partially enlarged view of FIG.

The thin film thermistor 5, which is a heat-sensitive element, is placed and bonded in the depressions 6f and 7f of the metal plates 2 and 3 in the lead frame A thus configured. That is, a brazing material such as a solder paste is applied to the depressions 6f and 7f in advance by a known method such as screen printing, or a brazing material such as a solder paste is preliminarily applied to the electrode surface 5c of the thin film thermistor 5. The thin film thermistor 5 is applied by coating, is placed in the recesses 6f and 7f so that the electrode surfaces 5c of the thin film thermistor 5 are superposed on each other, and is joined by a method such as heating to be electrically connected.

When the depressions 6f and 7f are formed at the tips of the narrow portions 2d and 3d, the thin film thermistor 5 is placed in the depressions 6f and 7f, and the electrode surface 5c is joined to the electrode surface 5c by the brazing material. Since the thin film thermistor 5 is fixed in the depressions by the depressions 6f, 7f when the brazing filler metal is melted by the heating at the time, it is possible to accurately position and join without using a special jig or the like. Is.

Further, holes (not shown) are provided in the depressions 6f and 7f as necessary, so that when the excessive brazing filler metal is heated and melted, the excess brazing filler metal is exposed to the back surface through the holes, thereby allowing the metal plate and the thin film thermistor to pass through. The electrode surfaces can be joined more firmly.

As described above, the cross-sections of the narrow portions 2d 1 and 3d of the metal plates 2 and 3 to which the thin film thermistor 5 is joined are flat as shown in FIGS. It can be brought into surface contact with a temperature detection target such as a roll.

Since the thin film thermistor 5 is used, the heat sensitive film 5b is provided on the insulating substrate 5a. Therefore, even if the thin film thermistor 5 is brought into direct contact with the temperature detection object, the heat sensitive film 5b Comes into contact with the temperature detection target through the insulating substrate 5a, and is electrically insulated from the temperature detection target.

Further, the fact that they are in surface contact as described above, and the use of alumina for the insulating substrate 5b, coupled with the fact that alumina is excellent in thermal conductivity, makes the thermal response characteristic of a conventional temperature sensor comparable to that of the conventional temperature sensor. It can be very excellent in comparison. Moreover, since the thin film thermistor 5 is surface-bonded to the tips of the narrow portions 2d and 3d, sufficient strength against torsion and vibration when attached to a device as a temperature sensor can be obtained.

Further, as the thin film thermistor 5 is provided from the wide portions 2b and 3b to the tips of the narrow portions 2d and 3d, the outer side is inclined and the width is gradually narrowed. The heat is less likely to be conducted to the wide portions 2b and 3b, and the elasticity with respect to the thin film thermistor 5 is made proper so that the thin film thermistor 5 and the temperature detection object can be smoothly contacted.

The thermal response characteristics of the above-mentioned two examples did not change in the vicinity of the thin film thermistor 5, and the thermal time constant was measured in order to investigate the thermal response characteristics. The thermal time constant is 63.2% (123 °) of a temperature span of 155 ° C from 25 ° C to 180 ° C when the temperature sensor is brought into contact with a temperature-controlled object whose temperature is controlled at 180 ° C. It is the time required to reach C).

In the present embodiment, the resistance-temperature characteristic of the temperature sensor to be measured in advance is measured, the resistance values at 25 ° C. and 123 ° C. are obtained, and the temperature sensor is brought into contact with the temperature-measuring object, The measurement was started at the resistance value at ° C, and the measurement was stopped when the resistance value at 123 ° C was reached, and the time during this period was obtained.

In the temperature sensor described in the above-mentioned Japanese Patent Laid-Open No. 63-205530, the thermal time constant was 1.8 seconds, but in the present embodiment, it was 0.3 seconds, which is lower than the conventional one. It can be seen that the thermal response characteristics are significantly improved.

[0038]

[Effect of the device]

 The present invention, as described above, places the thin-film heat sensitive element between the tips of a pair of elongated metal plates whose tips are thin by making the outer sides of the tips slanted. Since the heat sensitive element is brought into direct contact with the temperature sensing object, the heat capacity near the heat sensitive element can be made smaller than that of the conventional temperature sensor. Can be improved.

Moreover, the elongated metal plate supporting the thin-film heat sensitive element not only acts as an elastic body that brings the heat sensitive element into contact with the temperature-detected body with an appropriate pressing force because of its shape, but also from the heat sensitive element. It is also used as an electrical leader. Furthermore, since it is possible to continuously form the metal plate as a lead frame on one side of the strip and transfer-mold the holder, the number of assembly parts and the number of assembly steps can be simplified, and automatic assembly is also possible. It will be possible.

Further, since the heat-sensitive element used in the present invention has a thin film structure in which a heat-sensitive film is formed on an insulating substrate such as ceramic, when this temperature sensor is installed to measure the temperature of the temperature-sensing object, Since the heat-sensitive film comes into contact with the temperature-detected body through the insulating substrate, there is no need to perform any special insulation treatment, and the structure can be simplified.

Further, since the heat-sensitive element is placed in the recess formed in the narrow portion of the metal plate and electrically connected, the heat-sensitive element can be connected and fixed in the correct position in the correct direction, and the positional deviation may occur. This has the effect of improving the variation in the thermal response characteristics caused by the above.

[Brief description of drawings]

FIG. 1 is a plan view of a lead frame according to a first embodiment of the present invention.

FIG. 2 is a plan view in which a holder is formed on the above lead frame.

FIG. 3 is a perspective view of a thin film thermistor.

FIG. 4 is a perspective view showing a state where FIG. 2 is separated.

FIG. 5 is a sectional view taken along line BB of the above.

FIG. 6 is a plan view of a lead frame according to a second embodiment of the present invention.

FIG. 7 is a plan view in which a holding body is formed on the above lead frame.

FIG. 8 is a perspective view showing a state where FIG. 7 is separated.

FIG. 9 is a perspective view in which an external lead wire is connected to the same as above.

FIG. 10 is a side view showing a state in which the temperature sensors of FIG. 8 are stacked.

FIG. 11 is a plan view of a lead frame according to a third embodiment of the present invention.

FIG. 12 is a partially enlarged perspective view of the above.

FIG. 13 is a sectional view showing a state in which a thin film thermistor is attached.

[Explanation of symbols]

 A lead frame 2,3 metal plate 2d, 3d narrow part 2e, 3e connection terminal 4 holder 5 thin film thermistor 5a insulating substrate 5b heat sensitive film 6f, 7f recess 6 external lead wire

Claims (2)

[Scope of utility model registration request] 1. A pair of elongated metal plates having a connection terminal for connecting an external lead wire at one end and a narrow portion for joining a heat-sensitive element described later at the other end, and the pair of metal plates. Of a thin film thermistor in which a heat-sensitive film is formed on an insulating substrate, and two electrode surfaces are formed on the heat-sensitive film. A temperature sensor, comprising: 2. The temperature sensor according to claim 1, wherein a recess having substantially the same size as that of the heat sensitive element is formed at a tip of the narrow portion, and the heat sensitive element is bonded and fixed to the recess.